Yes, they do seem to be a hardy type of tetra. I have one that has been around a long time. I had three neon tetras and three phantom tetras.
I don't know what happened but all my neons died in a little over a year, 2 of the phantom died shortly after but one phantom is still hanging around and it's been almost two years now. I also have 2 plecos that have been in the tank since I started fishkeeping.
I would like to get about 5 more phantoms because they are pretty hardy and I think a small school would be neat.